1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  S390 version
4 *    Copyright IBM Corp. 1999, 2000
5 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
6 *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
7 *
8 *  Derived from "arch/i386/kernel/traps.c"
9 *    Copyright (C) 1991, 1992 Linus Torvalds
10 */
11
12/*
13 * 'Traps.c' handles hardware traps and faults after we have saved some
14 * state in 'asm.s'.
15 */
16#include "asm/irqflags.h"
17#include "asm/ptrace.h"
18#include <linux/kprobes.h>
19#include <linux/kdebug.h>
20#include <linux/randomize_kstack.h>
21#include <linux/extable.h>
22#include <linux/ptrace.h>
23#include <linux/sched.h>
24#include <linux/sched/debug.h>
25#include <linux/mm.h>
26#include <linux/slab.h>
27#include <linux/uaccess.h>
28#include <linux/cpu.h>
29#include <linux/entry-common.h>
30#include <asm/asm-extable.h>
31#include <asm/vtime.h>
32#include <asm/fpu.h>
33#include "entry.h"
34
35static inline void __user *get_trap_ip(struct pt_regs *regs)
36{
37	unsigned long address;
38
39	if (regs->int_code & 0x200)
40		address = current->thread.trap_tdb.data[3];
41	else
42		address = regs->psw.addr;
43	return (void __user *) (address - (regs->int_code >> 16));
44}
45
46#ifdef CONFIG_GENERIC_BUG
47int is_valid_bugaddr(unsigned long addr)
48{
49	return 1;
50}
51#endif
52
53void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
54{
55	if (user_mode(regs)) {
56		force_sig_fault(si_signo, si_code, get_trap_ip(regs));
57		report_user_fault(regs, si_signo, 0);
58        } else {
59		if (!fixup_exception(regs))
60			die(regs, str);
61        }
62}
63
64static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
65{
66	if (notify_die(DIE_TRAP, str, regs, 0,
67		       regs->int_code, si_signo) == NOTIFY_STOP)
68		return;
69	do_report_trap(regs, si_signo, si_code, str);
70}
71NOKPROBE_SYMBOL(do_trap);
72
73void do_per_trap(struct pt_regs *regs)
74{
75	if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
76		return;
77	if (!current->ptrace)
78		return;
79	force_sig_fault(SIGTRAP, TRAP_HWBKPT,
80		(void __force __user *) current->thread.per_event.address);
81}
82NOKPROBE_SYMBOL(do_per_trap);
83
84static void default_trap_handler(struct pt_regs *regs)
85{
86	if (user_mode(regs)) {
87		report_user_fault(regs, SIGSEGV, 0);
88		force_exit_sig(SIGSEGV);
89	} else
90		die(regs, "Unknown program exception");
91}
92
93#define DO_ERROR_INFO(name, signr, sicode, str) \
94static void name(struct pt_regs *regs)		\
95{						\
96	do_trap(regs, signr, sicode, str);	\
97}
98
99DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
100	      "addressing exception")
101DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
102	      "execute exception")
103DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
104	      "fixpoint divide exception")
105DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
106	      "fixpoint overflow exception")
107DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
108	      "HFP overflow exception")
109DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
110	      "HFP underflow exception")
111DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
112	      "HFP significance exception")
113DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
114	      "HFP divide exception")
115DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
116	      "HFP square root exception")
117DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
118	      "operand exception")
119DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
120	      "privileged operation")
121DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
122	      "special operation exception")
123DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
124	      "transaction constraint exception")
125
126static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
127{
128	int si_code = 0;
129	/* FPC[2] is Data Exception Code */
130	if ((fpc & 0x00000300) == 0) {
131		/* bits 6 and 7 of DXC are 0 iff IEEE exception */
132		if (fpc & 0x8000) /* invalid fp operation */
133			si_code = FPE_FLTINV;
134		else if (fpc & 0x4000) /* div by 0 */
135			si_code = FPE_FLTDIV;
136		else if (fpc & 0x2000) /* overflow */
137			si_code = FPE_FLTOVF;
138		else if (fpc & 0x1000) /* underflow */
139			si_code = FPE_FLTUND;
140		else if (fpc & 0x0800) /* inexact */
141			si_code = FPE_FLTRES;
142	}
143	do_trap(regs, SIGFPE, si_code, "floating point exception");
144}
145
146static void translation_specification_exception(struct pt_regs *regs)
147{
148	/* May never happen. */
149	panic("Translation-Specification Exception");
150}
151
152static void illegal_op(struct pt_regs *regs)
153{
154        __u8 opcode[6];
155	__u16 __user *location;
156	int is_uprobe_insn = 0;
157	int signal = 0;
158
159	location = get_trap_ip(regs);
160
161	if (user_mode(regs)) {
162		if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
163			return;
164		if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
165			if (current->ptrace)
166				force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
167			else
168				signal = SIGILL;
169#ifdef CONFIG_UPROBES
170		} else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
171			is_uprobe_insn = 1;
172#endif
173		} else
174			signal = SIGILL;
175	}
176	/*
177	 * We got either an illegal op in kernel mode, or user space trapped
178	 * on a uprobes illegal instruction. See if kprobes or uprobes picks
179	 * it up. If not, SIGILL.
180	 */
181	if (is_uprobe_insn || !user_mode(regs)) {
182		if (notify_die(DIE_BPT, "bpt", regs, 0,
183			       3, SIGTRAP) != NOTIFY_STOP)
184			signal = SIGILL;
185	}
186	if (signal)
187		do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
188}
189NOKPROBE_SYMBOL(illegal_op);
190
191DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
192	      "specification exception");
193
194static void vector_exception(struct pt_regs *regs)
195{
196	int si_code, vic;
197
198	if (!cpu_has_vx()) {
199		do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
200		return;
201	}
202
203	/* get vector interrupt code from fpc */
204	save_user_fpu_regs();
205	vic = (current->thread.ufpu.fpc & 0xf00) >> 8;
206	switch (vic) {
207	case 1: /* invalid vector operation */
208		si_code = FPE_FLTINV;
209		break;
210	case 2: /* division by zero */
211		si_code = FPE_FLTDIV;
212		break;
213	case 3: /* overflow */
214		si_code = FPE_FLTOVF;
215		break;
216	case 4: /* underflow */
217		si_code = FPE_FLTUND;
218		break;
219	case 5:	/* inexact */
220		si_code = FPE_FLTRES;
221		break;
222	default: /* unknown cause */
223		si_code = 0;
224	}
225	do_trap(regs, SIGFPE, si_code, "vector exception");
226}
227
228static void data_exception(struct pt_regs *regs)
229{
230	save_user_fpu_regs();
231	if (current->thread.ufpu.fpc & FPC_DXC_MASK)
232		do_fp_trap(regs, current->thread.ufpu.fpc);
233	else
234		do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
235}
236
237static void space_switch_exception(struct pt_regs *regs)
238{
239	/* Set user psw back to home space mode. */
240	if (user_mode(regs))
241		regs->psw.mask |= PSW_ASC_HOME;
242	/* Send SIGILL. */
243	do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
244}
245
246static void monitor_event_exception(struct pt_regs *regs)
247{
248	if (user_mode(regs))
249		return;
250
251	switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
252	case BUG_TRAP_TYPE_NONE:
253		fixup_exception(regs);
254		break;
255	case BUG_TRAP_TYPE_WARN:
256		break;
257	case BUG_TRAP_TYPE_BUG:
258		die(regs, "monitor event");
259		break;
260	}
261}
262
263void kernel_stack_overflow(struct pt_regs *regs)
264{
265	bust_spinlocks(1);
266	printk("Kernel stack overflow.\n");
267	show_regs(regs);
268	bust_spinlocks(0);
269	panic("Corrupt kernel stack, can't continue.");
270}
271NOKPROBE_SYMBOL(kernel_stack_overflow);
272
273static void __init test_monitor_call(void)
274{
275	int val = 1;
276
277	if (!IS_ENABLED(CONFIG_BUG))
278		return;
279	asm volatile(
280		"	mc	0,0\n"
281		"0:	xgr	%0,%0\n"
282		"1:\n"
283		EX_TABLE(0b,1b)
284		: "+d" (val));
285	if (!val)
286		panic("Monitor call doesn't work!\n");
287}
288
289void __init trap_init(void)
290{
291	unsigned long flags;
292	struct ctlreg cr0;
293
294	local_irq_save(flags);
295	cr0 = local_ctl_clear_bit(0, CR0_LOW_ADDRESS_PROTECTION_BIT);
296	psw_bits(S390_lowcore.external_new_psw).mcheck = 1;
297	psw_bits(S390_lowcore.program_new_psw).mcheck = 1;
298	psw_bits(S390_lowcore.svc_new_psw).mcheck = 1;
299	psw_bits(S390_lowcore.io_new_psw).mcheck = 1;
300	local_ctl_load(0, &cr0);
301	local_irq_restore(flags);
302	local_mcck_enable();
303	test_monitor_call();
304}
305
306static void (*pgm_check_table[128])(struct pt_regs *regs);
307
308void noinstr __do_pgm_check(struct pt_regs *regs)
309{
310	unsigned int trapnr;
311	irqentry_state_t state;
312
313	regs->int_code = S390_lowcore.pgm_int_code;
314	regs->int_parm_long = S390_lowcore.trans_exc_code;
315
316	state = irqentry_enter(regs);
317
318	if (user_mode(regs)) {
319		update_timer_sys();
320		if (!static_branch_likely(&cpu_has_bear)) {
321			if (regs->last_break < 4096)
322				regs->last_break = 1;
323		}
324		current->thread.last_break = regs->last_break;
325	}
326
327	if (S390_lowcore.pgm_code & 0x0200) {
328		/* transaction abort */
329		current->thread.trap_tdb = S390_lowcore.pgm_tdb;
330	}
331
332	if (S390_lowcore.pgm_code & PGM_INT_CODE_PER) {
333		if (user_mode(regs)) {
334			struct per_event *ev = &current->thread.per_event;
335
336			set_thread_flag(TIF_PER_TRAP);
337			ev->address = S390_lowcore.per_address;
338			ev->cause = S390_lowcore.per_code_combined;
339			ev->paid = S390_lowcore.per_access_id;
340		} else {
341			/* PER event in kernel is kprobes */
342			__arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
343			do_per_trap(regs);
344			goto out;
345		}
346	}
347
348	if (!irqs_disabled_flags(regs->psw.mask))
349		trace_hardirqs_on();
350	__arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
351
352	trapnr = regs->int_code & PGM_INT_CODE_MASK;
353	if (trapnr)
354		pgm_check_table[trapnr](regs);
355out:
356	local_irq_disable();
357	irqentry_exit(regs, state);
358}
359
360/*
361 * The program check table contains exactly 128 (0x00-0x7f) entries. Each
362 * line defines the function to be called corresponding to the program check
363 * interruption code.
364 */
365static void (*pgm_check_table[128])(struct pt_regs *regs) = {
366	[0x00]		= default_trap_handler,
367	[0x01]		= illegal_op,
368	[0x02]		= privileged_op,
369	[0x03]		= execute_exception,
370	[0x04]		= do_protection_exception,
371	[0x05]		= addressing_exception,
372	[0x06]		= specification_exception,
373	[0x07]		= data_exception,
374	[0x08]		= overflow_exception,
375	[0x09]		= divide_exception,
376	[0x0a]		= overflow_exception,
377	[0x0b]		= divide_exception,
378	[0x0c]		= hfp_overflow_exception,
379	[0x0d]		= hfp_underflow_exception,
380	[0x0e]		= hfp_significance_exception,
381	[0x0f]		= hfp_divide_exception,
382	[0x10]		= do_dat_exception,
383	[0x11]		= do_dat_exception,
384	[0x12]		= translation_specification_exception,
385	[0x13]		= special_op_exception,
386	[0x14]		= default_trap_handler,
387	[0x15]		= operand_exception,
388	[0x16]		= default_trap_handler,
389	[0x17]		= default_trap_handler,
390	[0x18]		= transaction_exception,
391	[0x19]		= default_trap_handler,
392	[0x1a]		= default_trap_handler,
393	[0x1b]		= vector_exception,
394	[0x1c]		= space_switch_exception,
395	[0x1d]		= hfp_sqrt_exception,
396	[0x1e ... 0x37] = default_trap_handler,
397	[0x38]		= do_dat_exception,
398	[0x39]		= do_dat_exception,
399	[0x3a]		= do_dat_exception,
400	[0x3b]		= do_dat_exception,
401	[0x3c]		= default_trap_handler,
402	[0x3d]		= do_secure_storage_access,
403	[0x3e]		= do_non_secure_storage_access,
404	[0x3f]		= do_secure_storage_violation,
405	[0x40]		= monitor_event_exception,
406	[0x41 ... 0x7f] = default_trap_handler,
407};
408
409#define COND_TRAP(x) asm(			\
410	".weak " __stringify(x) "\n\t"		\
411	".set  " __stringify(x) ","		\
412	__stringify(default_trap_handler))
413
414COND_TRAP(do_secure_storage_access);
415COND_TRAP(do_non_secure_storage_access);
416COND_TRAP(do_secure_storage_violation);
417